Hypertrophic cardiomyopathy (HCM) in the infant of the diabetic mother is thought to result from increased fetal insulin production during the third trimester. The purpose of this study is to examine whether iatrogenic HCM in premature infants might be induced by the routine neonatal therapies including the administration of hyperalimentation, dexamethasone or insulin infusion. Infants with gestational age < 32 weeks and birth weights < 1250 grams were studied. Echocardiographic and metabolic analyses were performed before 48 hours of age (enrollment), and at one, two, three, five and twelve weeks thereafter. Infants of diabetic mothers were excluded.

Six patients have been studied with a median gestational age of 26 wks(range 24-29 wks) and a median birth weight of 770 gms (range 609-1230 gms). All 6 subjects received hyperalimentation, 4 received dexamethasone, and 2 received both dexamethasone and an exogenous insulin infusion. The ratio of interventricular septal to left ventricular posterior wall thickness increased significantly from 1.2±0.1 at enrollment to 1.4±0.1 (p<0.05) during the third week of life, consistent with HCM. This ratio returned to a normal value of 1.1±0.1 by the fifth week of life. Caloric intake increased during the first three weeks to 116±7 kcal/kg/day in the third week, and hyperglycemia was common among subjects. C-peptide excreted in the urine peaked during the fourth week of life at 196±64 μg/g creatinine, and a peak in circulating insulin levels to 20±4 μU/ml occurred during the third week of life. Both the excreted c-peptide and circulating insulin levels decreased by the end of the fifth week. All results are expressed as the mean±SEM.

This preliminary data suggests that the development of a transient hypertrophic cardiomyopathy occurs in premature infants, and appears to resolve as caloric intake, insulin production and circulating insulin levels decrease.